Strawberry ripeness calibrated 2D colour lookup table for field-deployable computer vision

Abstract

Efficient strawberry harvesting using semi-autonomous robotic pickers requires a method for fast, automatic discrimination between ripe and unripe berries. In this paper we present a strawberry ripeness algorithm that has been developed and tested on images obtained with commercial cameras, recorded under daylight illumination on an outdoor strawberry farm. The method uses a 2D lookup table seeded such that regions for ripe strawberry, unripe strawberry and strawberry calyx exist in distinct locations in the table. Measurements show the ratio of ripe to unripe area provides a good estimator of ripeness and that the approach was practical for further extension to real-time use.